WO2020223645A1 - Capteur et système de détection et de réponse à des changements de composante de courant de déplacement d'impédance de fluides en tant qu'indicateur de changements de constante diélectrique - Google Patents

Capteur et système de détection et de réponse à des changements de composante de courant de déplacement d'impédance de fluides en tant qu'indicateur de changements de constante diélectrique Download PDF

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Publication number
WO2020223645A1
WO2020223645A1 PCT/US2020/031060 US2020031060W WO2020223645A1 WO 2020223645 A1 WO2020223645 A1 WO 2020223645A1 US 2020031060 W US2020031060 W US 2020031060W WO 2020223645 A1 WO2020223645 A1 WO 2020223645A1
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Prior art keywords
electrode
displacement current
sensor
body fluid
recited
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PCT/US2020/031060
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English (en)
Inventor
Terrence R. Hudrlik
Daniel C. HUDRLIK
Original Assignee
Hudrlik Terrence R
Hudrlik Daniel C
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Application filed by Hudrlik Terrence R, Hudrlik Daniel C filed Critical Hudrlik Terrence R
Publication of WO2020223645A1 publication Critical patent/WO2020223645A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/20—Measuring for diagnostic purposes; Identification of persons for measuring urological functions restricted to the evaluation of the urinary system
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
    • A61B5/14507—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue specially adapted for measuring characteristics of body fluids other than blood
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
    • A61B5/1468—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means
    • A61B5/1473—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means invasive, e.g. introduced into the body by a catheter

Definitions

  • the present invention generally relates to sensors and systems for detecting and responding to changes in the displacement current component of the impedivity of fluids as an indicator of dielectric constant changes in the fluids.
  • the present invention relates to sensors and systems for detecting changes in the displacement current component of impedivity of fluids as an indicator of dielectric constant changes.
  • Typical exemplary embodiments of the present inventions are sensors and systems for monitoring quality, purity or contamination of various fluids such as water, oil, consumable or industrial fluids, and organic or inorganic solutes.
  • an obj ect of the present invention provides a sensor for determining the dielectric constant of a body fluid, comprising a cannula having a distal end suitable for in vivo insertion; and a first electrode and a second electrode in the distal end for measuring the displacement current between the electrodes when inserted in the body fluid.
  • the sensor further comprises an amplifier to transduce and amplify the displacement current signal.
  • the sensor yet further comprises a third electrode that is capacitively coupled to the first electrode through a reference dielectric for a reference displacement current for comparison with the displacement current.
  • the first electrode and the second electrode may form a first capacitive element.
  • the first electrode and the third electrode form a second capacitive element.
  • the first electrode may comprise a pair of electrodes that are connected, a first one of the pair of the electrodes for the first capacitive element, and a second one of the pair of the electrode for the second capacitive element.
  • the reference dielectric is a solid or liquid. Furthermore, the reference dielectric may be a medical grade polymer or oil.
  • the third electrode may be enclosed within the first electrode.
  • the sensor may further comprise a fourth electrode and fifth electrode spaced apart from the distal end, forming a third capacitive element for measuring another displacement current in the body fluid.
  • the sensor may yet further comprises first and second CiFETs, wherein the second electrode and third electrodes are respectively connected to the iPorts of the CiFETs.
  • the iPorts are NiPorts of the first and second CiFETs.
  • [6] According to another obj ect of the present invention, it provides a method of measuring changes in the dielectric constant of a body fluid based on changes in a displacement current of the body fluid, the method comprising the steps of: (a) providing a tubular member adapted for insertion into a human body, having at least first and second capacitors respectively having first and second displacement current channels; (b). inserting the tubular member into the body such that only the first displacement current channel contacts the body fluid; and (c). measuring displacement currents in the first displacement current channel and the second displacement current channel for determining the changes in the dielectric constant.
  • [7] According to further obj ect of the present invention, it provides a method of analyzing a body fluid to detect the relative concentration of a constituent in the fluid, comprising: (a) providing a first electrode and a second electrode, and capacitively coupling the first electrode to the second electrode in the fluid; (b). measuring the displacement current component of the impedivity of the fluid between the first and second electrodes; and, (c). comparing the measured displacement current component with a reference value.
  • the reference value may be derived from a reference dielectric measured value.
  • the present invention provides a method for maintaining the solute level in a body fluid with a predetermined range: (a) providing a first electrode and a second electrode in the body fluid; (b). measuring a displacement current between the first and second electrodes in the body fluid to determine whether the displacement current is within the predetermined range; and, (c). injecting a predetermined amount of additives to the body fluid, if the solute level is outside the predetermined range.
  • Figure la is a schematic diagram of a sensor for measuring displacement current component of the impedivity of a body fluid in a pacing tip of a cardiac pacemaker according to a preferred embodiment of the present invention
  • Figure lb is a schematic diagram of the electrical circuit of the displacement current sensor shown in Figure la;
  • Figure 2a is a schematic diagram of a displacement current sensor circuit with separate sensing structures passively connected according to another preferred embodiment of the present invention
  • Figure 2b is a schematic diagram of a sensor circuit with separate sensing structures actively connected according to yet another preferred embodiment of the present invention.
  • FIG. 3 is a schematic diagram of a complimentary current injection field effect transistor (“CiFET”) symbol and 3-D cross-section with port locations;
  • FIG. 4 is a schematic diagram of a sensor circuit with CiFETs according to yet another preferred embodiment of the present invention.
  • Figure 5 is a schematic diagram of a sensor circuit with an external active source drive according to yet another preferred embodiment of the present invention.
  • Figure 6 is a schematic diagram of a sensor circuit illustrating integrated circuit dimensions according to yet another preferred embodiment of the present invention.
  • FIG. 7 is a schematic block diagram of the control-loop according to yet another embodiment of the present invention.
  • a preferred embodiment of the present invention is based on the realization that changes in the impedance or volume impedivity of body parts and or body fluids provide important data as to the condition and operation of various body functions.
  • This structure measures an aspect of that impedance as it is related to the body fluid’s chemical composition and as that composition affects its dielectric constant.
  • This structure utilizes electrodes that employ capacitive elements which pass displacement current that in turn depends on that capacitor's dielectric constant.
  • the dielectric of the body fluid will change as its ionic composition concentration changes. Changing the body fluid’s ionic solute concentrations with a non-polar solute like sugar will change the body fluid’s effective dielectric constant. It is important to know if the sugar level is changing and, importantly, how fast it is changing.
  • the rate of change of sugar level is often as important as its quantitative value.
  • the displacement current flows either due to internal excitations, depolarizations, or external frequency-controlled excitations.
  • the change in displacement current may be the input into a feedback loop that is then used to control the introduction of the additives that would bring the solute levels back into bounds.
  • the exposed dielectric may be prefilled with a specialized dielectric that when exposed to the target immersing solutions which diffuses into the interelectrode void may undergo a specialized reaction that changes that special dielectric so as to amplify the change in that specialized dielectric that elicits a specific dielectric response to the presence of that solute in the exposing solution.
  • This prefilled dielectric may also have ablative properties so that if part of the specialized dielectric is consumed by the reaction new specialized dielectric is exposed, this process will extend the useful life of such a probe.
  • FIG. 20 shows a body fluid sensor structure 100a that may be adapted to be placed on a cannula having an axis and a distal end, which is further adapted for insertion into the human body according to a preferred embodiment of the present invention.
  • a typically bipolar pacing lead / pacing tip electrode 110a is a 7-French or 2.3 mm diameter cannula.
  • Proximal to the pacing tip electrode 110a is a ring electrode 117a.
  • the tip electrode 110a embeds itself in the cardiac tissue, the ring electrode 117a floats in the cardiac chamber. This design represents an important advancement over prior art lead designs which are incapable of providing a reference displacement channel as well as localized tip and ring body fluid displacement current measurements.
  • the tip electrode 110a as well as the ring electrode 117a may just float in the fluid volume, such as blood, etc.
  • the tip electrode 110a and the ring electrode 117a may be inserted into a kidney and measure the urine's dielectric constant.
  • This embodiment features a cavity 112a inside the pacing tip electrode 110a with a suspended electrode 14a.
  • the electrode 14a is surrounded by a stable reference dielectric 15a.
  • This reference dielectric 15a is inserted inside the captive void 112a, between electrodes 13a and 14a at the time of manufacture.
  • the reference dielectric 15a may be a liquid, such medical grade oil, or solid, such as medical grade polymers.
  • the void 112a filled by the reference dielectric 15a has no access to the body fluids and forms a stable reference capacitance (or reference capacitor), formed between the common electrode 13a and the suspended electrode 14a with the reference dielectric 15a therebetween.
  • the shape of the void 112a may be irregular as its cell constant, value of that capacitor may be determined under known conditions during calibration.
  • the diameter of a 7 French electrode tip is 2.3 mm.
  • the distal end 115a of the tip electrode 110a may be arranged to contain a fractional 1mm void 112a that would provide this reference capacitor formed between electrodes 13a and 14a with the reference dielectric 15a.
  • the other capacitance exposed to the body fluids (or an exposed capacitor) would be in a concave shelter 116a in the distal end 115a of the tip electrode 110a for forming the exposed capacitor formed between a measuring electrode 11a and a common electrode 13a with a space (or dielectric) 10a.
  • the common electrode 13a shown in Figure la (which corresponds to electrode 13b shown in Figure lb), encases the reference capacitor and forms the common plate of both reference and exposed (or sensing) capacitors (corresponds to Cl and C2, respectively, in Figure lb).
  • the final size of these structural shapes will be adjusted to provide the largest capacitance possible so as to maximize the produced displacement current flows.
  • the original use / function as the pacing lead may/can still be taken place with the displacement current measurements, with electrical considerations that the common electrode 13a must be allowed to "float" to the local volume potential.
  • the common electrode 13a must be allowed to "float" to the local volume potential.
  • the pacing tip is being used to deliver a pacing beat, in this example, it must be electrically disconnected from the circuitry for pacing beat in such a manner that the common electrode 13a can be“float”.
  • measurements may be taken after a missed pacing beat so the local area "settles" down.
  • the measuring electrode 11a forms the other plate of an additional capacitor (or sensing capacitor C2 in Figure lb).
  • the space 10a between these electrodes 1 la and 13a would be filled with a fluid (i.e. body fluid).
  • body fluid i.e. body fluid
  • the measuring electrode 11a would be in the body fluid, while the common electrode 13a interfaces with the body fluid.
  • the body fluid acts as a dielectric 10b of the capacitor C2.
  • the value of this dielectric 10a / 10b may/would not be stable, and it may/would change over a period of time due to the ionic solute concentration changes in the body fluids.
  • capacitive elements may also be placed on the ring electrodes 117a as shown; where the capacitor is formed with the electrodes 12a andl6a, and the body fluids 17a which act as the dielectric 17b between the two capacitance electrodes 12a (or 12b) and 16a (or 16b).
  • the capacitor is formed with the electrodes 12a andl6a, and the body fluids 17a which act as the dielectric 17b between the two capacitance electrodes 12a (or 12b) and 16a (or 16b).
  • the capacitor is formed with the electrodes 12a andl6a, and the body fluids 17a which act as the dielectric 17b between the two capacitance electrodes 12a (or 12b) and 16a (or 16b).
  • the capacitor is formed with the electrodes 12a andl6a, and the body fluids 17a which act as the dielectric 17b between the two capacitance electrodes 12a (or 12b) and 16a (or 16b).
  • the body fluids 17a which act as the dielectric 17
  • FIG. lb is an electrical schematic of the capacitors in the lead tip and ring electrodes are shown as an electrical schematic.
  • the electrical schematic depicts the electrode- implemented capacitor plates shown in Figure la as connected and isolated capacitors.
  • the common drive electrode is 13a/13b in which each plate of the capacitors Ci and C2 produced in the tip electrode 110a and the ring 117a in Figure la is shown in the schematic embodiment shown in Figure lb and are electrically connected as they are in the embodiment of the electrode structure shown in Figure la.
  • the enclosing / common electrode 13b follows to the potential at its location.
  • the common electrode 13b provides a common drive through the dielectrics 10b and 15b.
  • the reference dielectric 15b is isolated from the body fluids and its value is constant and would not change with that fluid's concentration of composition.
  • the dielectric 10b represents the body fluid and, accordingly, it would change over a period with any changes in the body fluids composition.
  • a single capacitance C3 may be placed on the ring electrode 117a.
  • the ring electrode capacitance plate 12b will assume the structures local dynamic potential and supply the drive that produces displacement current flow drive through the dielectric 17b that is exposed to body fluid which in turn induces a charge on the electrodes plate 16b.
  • the capacitance value of the electrodes 13b and 14b exposed to the body fluid will change as the dielectric 10b of the body fluid changes.
  • the capacitance of the electrodes 12b and 16b will change as the dielectric 17b changes.
  • the capacitive construct based on the electrodes 12b and 16b with its body fluid dielectric 17b will be constantly awash in the blood found in its heart chamber.
  • Figure 2a shows a differential induced displacement current sensor comprises split halves thereof 200a and 210a, which are connected by a wire 20a.
  • the split halves 200a and 210a may be located near or distant from each other.
  • the encasing / common electrodes 25a and 25a’ are arranged to be at the same potential.
  • the reference dielectric 23a / 23a’ may be a liquid, such medical grade oil, or solid, such as medical grade polymers.
  • differential sensors 200a and 210a will be the same with the additional condition that the encasing electrodes 25a and 25a’ driving potential would now be a form of an averaged potential between the two locations.
  • the advantage such a configuration brings lies in the ability to measure the relative local dielectric constant changes across several fluid storage locations all referenced to their combined potential.
  • FIG. 3 shows a schematic diagram of a complimentary current injection field effect transistor (or“CiFET”) 300 and its 3-D cross-section with port locations.
  • the capabilities of the CiFET come from its unique structure shown in Figure 3.
  • the iPort terminals 3 Id (or 31a) and 32d (or 32a) one is able to design and incorporate analog capabilities into unmodified CMOS process nodes.
  • CiFET 300 comprising PiFET 302 and NiFET 301, laid out on the substrate (or body B + and B - respectively) like a mirror image along well border shown therein.
  • PiFET 302 comprises source terminal S + s34d , drain terminal D + d36d, and iPort control terminal Pi , defining source + channel 34d Between the source terminal S + and the iPort control terminal Pi diffusion region 32d, and drain + channel 36d between the drain terminal D + and the iPort control terminal Pi diffusion region 32d;
  • NiFET 301 also comprises source terminal S - s33d, drain terminal D - d35d, and iPort control terminal Ni , defining source - channel 33d between source - terminal S - s33d and the iPort control terminal Ni diffusion region 3 Id, and drain - channel 35d between drain - terminal D - d35d and the iPort control terminal Ni diffusion region 3 Id.
  • CiFET 300 further comprises a common gate terminal 30d over source + channel 34d, drain + channel 36d, source - channel 33d, and drain - channel 35d ( or 350 , 35e ) . Accordingly, the common gate terminal 30d is electrically coupled to the iPort control terminals Pi and Ni.
  • CiFETs 400a and 400b act as current-to-voltage converters.
  • the displacement current paths 42 and 43 will have gone through a current to voltage transformation via CiFETs 400a and 400b, respectively.
  • the output voltages of this transduction 45 a and 45b may still often be too small in magnitude to pass onto computation circuits and may require additional amplification and, optionally, need to have these DC offset shifted as is customary in an analog circuit chain.
  • the capacitance formed by the pair of electrodes 11a’ and 13a’ with body fluid as the dielectric 41 is connected to CiFET 400a via NiPort 40a.
  • the reference capacitor formed by the pair of electrodes 13a’ and 14a’ with the space / reference dielectric 15a’ is connected to a separate CiFET 400b via NiPort 40b.
  • the input resistance path to these capacitive displacement current paths 42 and 43 are adjusted by design to present a low resistance path to ground.
  • the respective displacement currents flow through their capacitive paths into the NiPort 40a and 40b of their respective CiFETs 400a and 400b and then is returned as displacement current the conductive solution via the reference electrode 44 connection thus completing the current loop.
  • the current into the respective NiPorts 40a and 40b are transformed by their CiFETs 400a and 400b to a proportional change in voltage on the outputs 45a and 45b of the respective CiFETs 400a and 400b.
  • the reference capacitance’s current proportional voltage change is seen on the output 45b and the current through the exposed capacitance is reflected as a change of voltage on the output 45a.
  • the outputs 45a and 45b are further connected to the plus and minus inputs of the differential amplifier 46 and that amplifier 46 produces the difference between those two outputs 45a and 45b. If the channel displacement currents are designed to be roughly equal at a specific nominal body fluid dielectric constant the differential of these two output voltages 45a, 45b, will produce a change detecting output voltage 47 not unlike that produced when a Whetstone bridge goes out of balance.
  • the differential amplifier 46 provides an output signal 47 that is directly reflective of the incremental changes in the exposed dielectric.
  • the output voltage 47 of the differential amplifier 46 would not be linearly proportional to a change in dielectric constant, rather, depending on the relative tuning of the displacement current magnitudes at a dielectric constant balance point the output voltage 47 will produce a non-linear response to the dielectric constant change and would serve as an initial indicator of changing dielectric constant.
  • This output voltage 47 is shown as an input to, for example, an A/D convertor (such as one shown in Figure 7) and could be used as a flag or early detection that would turn on the full microprocessors capabilities to analyze the change seen in the raw amplified signals / outputs 45a and 46a.
  • the CiFET is uniquely suited to making extremely low noise input signal current measurements.
  • the input impedances of NiPort 42 and 43 of the CiFETs 400a and 400b, respectively, are designed to have a low value to produce a virtual short circuit to the current flow 40a and 40b.
  • the displacement current 40a through the exposed capacitor formed between the electrodes 11a and 13a with the space 10a in Figure la, will change as its dielectric 41 (which corresponds to space 10a in Figure la) changes and can be used alone if desired. As the solution exposed dielectric changes its displacement current will shift in both phase and magnitude which will be reflected in the output voltages 45a and 45b.
  • the changes may be used to back calculate the quantitative changes in the solution exposed dielectric.
  • the changes may be used in a control loop where detailed analysis and estimation of the dielectric values are unnecessary as just the directional and rough estimation of the magnitude of that displacement current change with respect to a reference may be enough information. This later technique produces a very low overheard indication of the solution dielectric change.
  • the displacement currents 42 and 43 are shown as inputs to the NiPorts 40a and 40b of CiFETs 400a and 400b, respectively.
  • the displacement currents could also be injected into the PiPorts 49a and 49b of respective CiFETs 400a and 400b as an alternative.
  • the output voltages 45a and 45b will respond to current injection into these PiPorts 49a and 49b in the same fashion as to current injection into the shown NiPort injection 40a and 40b.
  • the term iPort connotes either NiPort or PiPort. A person of ordinary skilled in the art would recognize that current to voltage transformations may also be achieved using other known operational amplifier circuits as well.
  • FIG 5 another differential displacement current sensing system 500 according to another preferred embodiment of the present invention is shown placed in an environment where it is exposed to a conductive fluid 56 that flows by the sensor.
  • the fluid flow 56 is contained by the wall 57 in system 500.
  • the sensor system 500 comprises enclosing / common electrode 53 including a suspended electrode 51 in the conductive fluid 56 for measuring displacement current, and a reference electrode 52 in a reference dielectric 58 enclosed in the common electrode 53, whose functions are similar to those that have been detailed in Figure la and Figure 4.
  • the reference dielectric 58 may be a liquid, such medical grade oil, or solid, such as medical grade polymers.
  • the system 500 has no intrinsic signal drive, per se: it is inherently passive and requires an extrinsic signal source 50 and extra drive electrodes 54 and 55.
  • the active external electronic signal source 50 could be a voltage-controlled sine wave generator or a current source.
  • the active source 50 using electrodes 54 and 55 would introduce a signal drive into the conductive fluid 56 which will produce the dynamic potential which will be assumed by the common electrode 53.
  • An external active source 50 may also be used in-vivo. If the drive is sinusoidal the produced displacement channel currents will be sinusoidal and analysis of their magnitude and phase for the purpose of determining the actual quantitative details of the exposed dielectric changes would be easier than breaking down the harmonic components of a complex waveform such as the drive delivered by a heart depolarization.
  • the external signal generator 50 shown in Figure 5 could be directly connected to the common electrode 53 for actively and directly drive the common electrode 53 for measurements.
  • FIG. 6 presents an image of the cross section of a miniaturized version of the capacitive displacement current sensor 600 according to yet another preferred embodiment of the present invention.
  • the sensor 600 comprises enclosing (or common) electrode 63 with a protected secondary electrode 64 surrounded with a reference dielectric / space 65 and an electrode 66 that is exposed to dielectric / solution or conductive volume 67, which functions are similar to those that have been detailed in Figure la.
  • the reference dielectric 65 may be a liquid, such medical grade oil, or solid, such as medical grade polymers.
  • the space 67 between electrode 63 and electrode 66 may also be filled with either an ablative material or a material that provides a secondary reaction that would modify the presented fluid exposed dielectric when exposed to the desired target in the solution
  • Electrodes 66 and 64 are directly connected one each to the NiPort 60 and the PiPort 61, respectively, of the CiFET 610 and as an injection current into either iPorts 60 and 61 will cause the output voltage 62 to go up. If current is withdrawn from either of the two iPorts 60 and 61, the output voltage 62 will go down. The output voltage 62 will be a combination (or sum) of these currents, and, as it can be seen, a transduction circuit is significantly simplified and contained using the CiFET 610.
  • FIG. 7 is a schematic block diagram of a control system 700 according to yet another embodiment of the present invention.
  • the control system 700 comprises a displacement current sensor 710 that monitors changes in the displacement current component of impedivity of a fluid 77 as an indicator of dielectric constant changes thereof.
  • the exemplary displacement current sensors are shown in, at least, Figures 4 and 6.
  • One or more outputs DCSi, DSC2, ... DSC n from the displacement current sensor 710 are provided to a controller block 720. Those outputs DCSi, DSC2, ...
  • DSC n from the displacement current sensor 710 may include, but not limited to one or more of: one or more displacement currents (either current or converted voltage form) of the fluid 77 (at a single location or multiple locations in the fluid 77, such as the output 45a shown in Figure 4), one or more corresponding reference displacement currents (such as the reference output 45b shown in Figure 4), and one or differentials thereof (such as the differential output voltage 47 shown in Figure 4).
  • the controller block 720 comprises A/D converter(s) 71 for converting one or more outputs from the displacement current sensor 710 into digital data for further processing by a microprocessor(s) 70 or to be stored in a memory (ies) 72; the microprocessor(s) 70 for executing executable codes that may be stored in the memory (ies) 72 and processing the converted data from the A/D converters 71 for analysis; the memory(ies) or data storage 72 for storing data and/or executable code(s) for the microprocessor(s) 70; and, input/output communication 73 for wired or wireless communication.
  • the memory 72 may be a volatile and/or non-volatile memory, such as RAM, ROM, EEPROM, flash memory, solid state hard disc, or other data storage that may be used with microprocessor 70.
  • the controller block 720 is in communication with fluid pump drive unit 730, which includes, but not limited to: a control and communication module 74, which corresponds to and is in communication with input/output communication 73 of the controller block 720, and controls a fluid pump and drive unit 75; corrective fluid resolution 76 is a reservoir for a solution / additive or a storage for an additive(s) / compound(s) that may be released to the fluid 77 through the fluid pump and drive unit 75; and, the fluid pump and drive unit 75 that drives the pump to release the solution / additive from the corrective fluid resolution 76 through a port 78 into the fluid 77.
  • fluid pump drive unit 730 includes, but not limited to: a control and communication module 74, which corresponds to and is in communication with input/output communication 73 of the controller block 720, and controls a fluid pump and drive unit 75; corrective fluid resolution 76 is a reservoir for a solution / additive or a storage for an additive(s) / compound(s) that may be released to
  • the controller block 720 would utilize a differential output (such as the output 47 shown in Figure 4) between the displacement current of the fluid 77 and the reference displacement current as the initial indicator of changing dielectric constant of the fluid, and compares against a predetermined threshold level (or range of change). Such a predetermined threshold level / range may be stored in the memory 72. Based on the result of the comparison, the microprocessor 70 may start to carry out and measures the displacement current of the fluid 77 and the reference displacement current in order to determine whether to control the fluid pump drive unit 75. Such determination by the microprocessor 70 may be carried out by comparing the measured displacement current of the fluid 77 and the reference displacement current with predetermined threshold values, which may also be stored in the memory 72.
  • the controller block 720 further a timer (not shown) to account for some propagation delay in the fluid 77 to prevent the microprocessor 70 to make another measurements after the microprocessor 70 controls the fluid pump and drive unit 75 based on the previous measurement(s).

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Abstract

La présente invention concerne des capteurs et des systèmes pour détecter et répondre à des changements dans la composante de courant de déplacement de l'impédance de fluides en tant qu'indicateur de changements de constante diélectrique. Les capteurs comprennent une structure d'électrode unique, comprenant une première électrode et une seconde électrode dans une extrémité distale d'une canule pour mesurer le courant de déplacement entre les électrodes lorsqu'elle est insérée dans le fluide corporel. Facultativement, il y a une troisième électrode qui est couplée de manière capacitive à la première électrode par l'intermédiaire d'un diélectrique de référence pour un courant de déplacement de référence pour comparaison avec le courant de déplacement. Cette première électrode agit comme un entraînement commun, amenant un courant de déplacement à s'écouler à travers chacun des canaux capacitifs lorsque la composante de courant de déplacement de l'impédance du fluide change. Un ou plusieurs canaux capacitifs supplémentaires peuvent être présents dans la structure annulaire proximale de la canule sans l'électrode d'entraînement commune.
PCT/US2020/031060 2019-05-02 2020-05-01 Capteur et système de détection et de réponse à des changements de composante de courant de déplacement d'impédance de fluides en tant qu'indicateur de changements de constante diélectrique WO2020223645A1 (fr)

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